| 主权项 |
1. An offline power converter, comprising:
an input port configured to receive an input voltage; an output port configured to provide an output voltage; a rectifier coupled to the input port to receive the input voltage, and to provide a rectified DC voltage based on the input voltage; a normally-on power device coupled to the rectifier to receive the rectified DC voltage, and to provide a clipped voltage based on the rectified DC voltage; a power switch having a first terminal, a second terminal and a control terminal, the first terminal being coupled to the normally-on power device to receive the clipped voltage, the second terminal being coupled to the output port; a first comparator having a first input terminal configured to receive a first threshold, a second input terminal configured to receive a first sense signal indicative of the clipped voltage, and an output terminal configured to provide a first comparison signal based on the first threshold and the first sense signal; a second comparator having a first input terminal configured to receive a second threshold, a second input terminal configured to receive a second sense signal indicative of the rectified DC voltage, and an output terminal configured to provide a second comparison signal based on the second threshold and the second sense signal; and a logic and drive unit having a first input terminal coupled to the output terminal of the first comparator to receive the first comparison signal, a second input terminal coupled to the output terminal of the second comparator to receive the second comparison signal, and an output terminal configured to provide a driving signal to the control terminal of the power switch, the driving signal having a slow-sloping ramp down when the first sense signal goes higher than the first threshold, and having a substantial vertical ramp down when the second sense signal goes higher than the second threshold. |
